THURSDAY, Aug. 15 (HealthDay News) -- People who live at high altitudes and suffer from chronic mountain sickness may have their genes to thank, a new study finds.

About 140 million people worldwide live permanently at high altitudes, where oxygen levels are low. Many of them have adapted to their environment, but others have chronic mountain sickness, characterized by heart attacks, strokes and lung problems at an early age.

The new findings could point the way toward treating the condition, researchers say.

Chronic mountain sickness develops over time. It differs from acute mountain sickness, or altitude sickness, which usually strikes people within hours of reaching high altitude, often causing nausea, vomiting or headaches.

In this study, the researchers sequenced the entire genomes of 20 people living in the Andes, 10 with chronic mountain sickness and 10 without. The investigators found greater expression of two genes -- the blood cell regulator SENP1 and the cancer-associated gene ANP32D -- in people with chronic mountain sickness than in those without.

Reducing the expression of these two genes improved survival under low-oxygen conditions both in flies and in human cells, according to the study published Aug. 15 in the American Journal of Human Genetics.

"We showed that the genes that were identified by the whole-genome scan were actually linked causally to sickness in low-oxygen environments," study co-senior author Dr. Gabriel Haddad, of the University of California, San Diego, said in a journal news release.

"With further study, the two genes we identified and validated may become potential drug targets for treating conditions related to low oxygen levels, such as strokes and heart attacks. In addition, they may also be considered as targets for a potential drug treatment for chronic mountain sickness," Haddad said.